1. Field of the Invention
The present invention pertains to the field of refrigeration systems. More particularly, the present invention relates to safety devices operating in a refrigeration system to control the system and alert the owner in the event of refrigeration system breakdown.
2. BACKGROUND INFORMATION
Refrigeration systems have been known for years. An early example of a refrigerating apparatus can be found in U.S. Pat. No. 1,768,602. A typical refrigeration system of this sort uses a compressor which drives a refrigeration fluid through a closed-loop system. In one stage of the system, commonly called the condenser, the refrigerant fluid is pressurized and condensed to a liquid. During this transformation from the gaseous to the liquid state, the refrigerant fluid releases heat to the surrounding environment, often with the aid of a fan and heat dissipation fins or the like.
Cooled to near ambient temperature, the refrigerant fluid continues through the system to a refrigerant metering device such as a thermal expansion valve. The metering device provides a controlled release of the high pressure liquid into a series of coils in the system commonly called the evaporator. Upon passage through the metering device the refrigerant fluid undergoes a change of state from a high pressure liquid to a lower pressure gas. By the time the refrigerant fluid has reached the evaporator end furthest from the expansion valve, the refrigerant fluid is in a gaseous state at a relatively low pressure. The transformation from high pressure liquid to low pressure gas which occurs between the metering device and the far end of the evaporator results in the extraction of thermal energy from the atmosphere surrounding the evaporator. Beyond the evaporator, the refrigerant fluid is drawn into the compressor and begins the cycle anew.
Operation of the compressor of a refrigeration system is typically controlled in one of two ways. In some systems, a thermostat monitors the temperature in the vicinity of the evaporator and cycles the compressor accordingly. In other systems, compressor control is handled by a dual pressure switch which obtain its low pressure reading at the inlet side of the compressor and its high pressure reading at the outlet side. When the pressure at the outlet side reaches an upper limit, the compressor is activated and when the pressure at the inlet side reaches a lower limit it is deactivated.
A significant leak in a large scale refrigeration system can lead to the loss of thousands of dollars worth of refrigerant fluid by evaporation into the atmosphere and can result in an equally costly loss of food stuffs or other refrigerated contents. The nature of a refrigeration system, however, makes detection of system leaks difficult. Changes in ambient temperature and in the behavior of system components result in virtually continuous change in the system pressure and in the fluid flow rate at any particular point in the system. Because these two factors are the principle indicia of fluid condition, the task of leak detection is greatly complicated.